1. Technical Field of the Invention
The present invention relates to reaction or rocket engines and rocket thrust chambers such as found in a space vehicle. More particularly, the present invention is concerned with a rocket engine incorporating a solar thermal propulsion unit for generating thrust utilizing solar radiation.
2. Background Art
Propulsion systems and particularly propulsion systems utilized in space going vehicles are well known. The design and function of rocket engines vary considerably depending upon performance requirements.
Unmanned interplanetary probes and the like as well as those vehicles which may be used in the future for traversing distances between a space station, a lunar base or other destinations will bnefit significantly from high specific impulses but may only require a reduced thrust capability.
One known solar propulsion concept utilizes an alkali metal seed added to the propellant. The propellant is heated in a heat exchanger by solar radiation and thereafter the vapor or expanded gases are discharged from a convergent-divergent nozzle to effect suitable thrust. This type of system is heavy and requires a complex delivery system to feed the fuel to the heating element and thereafter convey the vapor to the nozzle exit.
Another concept utilizes a solar rocket absorber of rhenium tubes to heat liquid hydrogen which is then conveyed out of the convoluted rhenium tubes to a thruster. This design has limited performance capability and is difficult to manufacture.